Dental Tribune Israel Edition

5 Dental Tribune Israel | 11/2016 the margins of the prepared teeth (Pic. 14). A loose non-attached cord should be gently removed or partially cut using delicate, sharp scissors. In the case of the cord remaining at the sulcus bottom - it should be gently removed with the aid of a dental explorer and tweezers. The impression was then poured with a dental plaster to be used as a working model (Pics. 15a, b) on which the technician, Vincenzo Musella, DDS, MDT, Modena, Italy, produced two e.max restorations – monolithic and externally stained - (Pic. 16) that were later adhesively bonded to the teeth, under a rubber dam isolation (Pics. 17a-c). Discussion Various studies (1-4), confirm the single-step technique with PVS or PE to produce very accurate impressions; Several in vitro studies (8-11) have shown that the two-step putty/wash technique performed with PVS resulted in very accurate stone dies when a 2 mm relief was left in the preliminary putty impression. The use of a spacer during the preliminary putty impression has been also shown to provide as accurate results as the single-step technique (5). The accuracy of a two-step impression technique depends also on the ability to reduce the stress generated in the set putty during its reinsertion, and on the ability to provide sufficient space for the light body material. These steps are mandatory so that the pressure exerted on the set putty is as minimal as possible, in order to prevent any distortion, as upon its removal - the set putty will revert to its original dimensions. The technique described in this article utilizes undercuts elimination as well as venting channels in the set putty, to ensure just a minimal space for the light body and to enable free flow of all excess material. This minimizes the pressure exerted on the light body by the set putty. The light body material is not injected intra-orally but rather chairside, onto the set putty at the tray - which facilitates dramatically this delicate step. After insertion it fills the putty channels and captures the configuration of the prepared teeth up to the area of the deeper first cord, resulting in an accurate bubble-free perfect impression, in a simple and controlled manner. This technique may be more time consuming than the one step, due to the time required for the modification of the set putty. However, the technique described is not as sensitive as the traditional one-step and wash techniques, particularly when several teeth are to be treated. The light body material is more easily injected only onto the set putty chairside, rather than around the teeth intraorally. For these reasons the risk of air entrapment in the final impression, as might happen with the one-step or the traditional wash techniques, is eliminated. The set modified putty serves as a perfect matrix to direct and guide the light body to all areas between the putty and teeth structures, and to fill it, in its entirely, with no voids. The channeled – putty/wash technique has been utilized successfully by the authors, along with the various traditional techniques, for more than 30 years, for all indications of prepared teeth impressions, with excellent accurate results and with minimal adverse effects to the periodontium, in thousands of such impressions (Pics. 18-25). One should follow up meticulously each step of the described technique to avoid any uncontrolled effects. There is a learning curve to this technique, mainly due to the correct preparation/ modification of the set putty, prior to its reinsertion, and due to the individual force applied when sitting the light body loaded putty during the second insertion step. It should be stressed that this type of impression ends up in some very thin volumes of the light body and in some areas it might be completely missing, but the relief of the putty and the created channels enable a stress free venting of the light body excess, that results in perfectly accurate clinical results, as experienced by the authors. Conclusion Traditional elastomeric material impressions are still the technique of choice for most dentists, PVS being the most popular. The putty/ wash technique has been reported to be preferred by most dentists when prepared teeth have to be imprinted.However,impressionsare troublesome, mainly due to voids at the abutment margins and due to insufficient gingival deflection that prevents the material from reaching the whole apical area of the teeth. This article re-visits a previously describedtechniqueoriginallyutilized for condensation-type silicones, that has been modified and matched to modernPVS.Thetechniqueissimple to use and, when applied properly, causes no harm to the surrounding periodontiumandprovidesconsistent voids-free, predictable, accurate and flawless perfect impressions of prepared teeth. Acknowledgment The authors thank Vincenzo Musella, DDS, MDT, from Modena, Italy, for an outstanding collaboration and for the artistic ceramic creations presented here. References 1.Radicev I. Knife for groove cutting for escaping of the excessive correction silicon in two-phase two-layer impression with silicones. Stomatologia (Sofia) 1989; 71(1): 69-71. 2.Ting-shu Su. Sun Jian. Intra-oral digital impression technique: a Review. Journal of Prosthodontics 2014; 9. 3.Seelbach P, Brueckel C, Wostmann B. Accuracy of digital and conventional impression techniques and workflow. Clinical Oral Investigations 2012; 10. 4.Fradeani M, Barducci G. Esthetic rehabilitation in fixed prosthodontics, Quintessence 2008; 2. 5.Nissan J, Gross M, ShifmanA, Assif D. Effect of wash bulk on the accuracy of polyvinyl siloxane putty-wash impressions. Journal of Oral Rehabilitation 2002; 4: 357-361. 6.Nissan J, Laufer BZ, Brosh T, Assif D. Accuracy of three polyvinyl siloxane putty-wash impression techniques. Journal of Prosthetic Dentistry 2000; 83: 161-165. 7.Kopac I, Cvetko E, Marion L. Gingival inflammatory response induced by chemical retraction agents in beagle dogs. Int J Prosthodont 2002: 5(1): 14-19. 8.Hung SH, Purk JH, Tira DE, Eick JD. Accuracy of one-step versus two-step putty wash addition silicone impression technique. Journal of Prosthetic Dentistry 1992; 67(5): 583-589. 9.Idris B, Houston F, Claffey N. Comparison of the dimensional accuracy of one- and two-step techniques with the use of putty/wash addition silicone impression materials. Journal of Prosthetic Dentistry 1995; 74(5): 35-541. 10.Caputi S, Varvara G. Dimensional accuracy of resultant casts made by a monophase, one-step and two-step, and a novel two-step putty/light-body impression technique: an in vitro study. Journal of Prosthetic Dentistry 2008; 99(4,): 274-281. 11.Nissan J, Rosner O, Bukhari MA, Ghelfan O. Pilo R-Effect of various putty-wash impression techniques on marginal fit of cast crowns. Int.J Periodontics and Restorative Dent 2013; 33(1): 37-42. 12.Franco EB, Da cunha LF, Herrera FS, Benetti AR. Accuracy of single – step versus 2 step double-mix impression technique ISRN Dent 2011. Dr. Mirela Feraru D.M.D. * Dr. Galit Talmor D.M.D. * Prof. Nitzan Bichacho D.M.D. ** * Private Clinic, Tel Aviv, Israel ** Head - RE Goldstein Center of Esthetic dentistry, Dept. of Prosthodontics, Hadassah Faculty of Dental Medicine and the Hebrew University, Jerusalem; Private Clinic, Tel Aviv, Israel Pic. 17a: 2 years post op smile with the bonded e.max restorations. Note the perfect gingival and esthetic integration. The other teeth were also treated (orthodontically and restoratively) as part of the overall treatment; Pic. 17b: 2 years post op retracted view; Pic. 17c: Radiographic control at 2 years follow up. Pics 18-25: The channeled-putty / light body wash technique is implemented in numerous various impressions in a structured systematic approach for predictable perfect results. Pic. 17a Pic. 17b Pic. 17c Pic. 18 Pic. 19 Pic. 20 Pic. 21 Pic. 22 Pic. 23 Pic. 24 Pic. 25

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